LogViewerForm.cs

using NLog.Config;
using NLog;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace LogViewer
{
    public partial class LogViewerForm : Form
    {
        public LogViewerForm()
        {
            InitializeComponent();
            ListBoxTarget.ListBoxControl = listBoxLogs; // 绑定 ListBox
            listBoxLogs.MouseWheel += ListBoxLogs_MouseWheel;
        }

        private void LogViewerForm_Load(object sender, EventArgs e)
        {
            var config = new LoggingConfiguration();

            var listBoxTarget = new ListBoxTarget()
            {
                Name = "listbox",
                Layout = "${longdate} | ${level:uppercase=true} | ${message}"
            };

            config.AddTarget(listBoxTarget);
            config.AddRule(LogLevel.Trace, LogLevel.Fatal, listBoxTarget);

            LogManager.Configuration = config;

            var contextMenu = new ContextMenuStrip();
            var copyItem = new ToolStripMenuItem("复制");
            copyItem.Click += (s, ev) =>
            {
                if (listBoxLogs.SelectedItem != null)
                    Clipboard.SetText(listBoxLogs.SelectedItem.ToString());
            };
            contextMenu.Items.Add(copyItem);

            listBoxLogs.ContextMenuStrip = contextMenu;
        }

        private void btnApplyFilter_Click(object sender, EventArgs e)
        {
            string keyword = textFilter.Text.ToLower();
            string level = comboLevel.SelectedItem.ToString();

            listBoxLogs.Items.Clear();

            foreach (var log in ListBoxTarget.AllLogs)
            {
                bool levelMatch = (level == "All") || (log.Level.Name.Equals(level, StringComparison.OrdinalIgnoreCase));
                bool keywordMatch = string.IsNullOrEmpty(keyword) || log.FormattedMessage.ToLower().Contains(keyword);

                if (levelMatch && keywordMatch)
                {
                    string msg = $"{log.TimeStamp:yyyy-MM-dd HH:mm:ss.fff} {log.Level} {log.FormattedMessage}";
                    listBoxLogs.Items.Add(msg);
                }
            }
        }

        private void btnApplyFilter_Click_1(object sender, EventArgs e)
        {

        }

        private void listBoxLogs_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void LogWinForm_FormClosed(object sender, FormClosedEventArgs e)
        {
            ListBoxTarget.ListBoxControl = null;
        }

        private void listBoxLogs_KeyDown(object sender, KeyEventArgs e)
        {
            if (e.Control && e.KeyCode == Keys.C && listBoxLogs.SelectedItem != null)
            {
                Clipboard.SetText(listBoxLogs.SelectedItem.ToString());
            }
        }

        void CheckAutoScrollStatus()
        {
            // 检查是否在最底部
            int visibleItems = listBoxLogs.ClientSize.Height / listBoxLogs.ItemHeight;
            if (listBoxLogs.TopIndex + visibleItems >= listBoxLogs.Items.Count)
            {
                ListBoxTarget.autoScroll = true;  // 滚动条在最底部
            }
            else
            {
                ListBoxTarget.autoScroll = false; // 用户往上滚了
            }
        }

        private void ListBoxLogs_MouseWheel(object sender, MouseEventArgs e)
        {
            CheckAutoScrollStatus();
        }

        protected override void WndProc(ref Message m)
        {
            const int WM_VSCROLL = 0x115;
            if (m.Msg == WM_VSCROLL && m.HWnd == listBoxLogs.Handle)
            {
                CheckAutoScrollStatus();
            }
            base.WndProc(ref m);
        }

        private void textFilter_TextChanged(object sender, EventArgs e)
        {

        }
    }
}